Selective gate recess etching of GaInP/InGaAs/GaAs PHEMT using BCl/sub 3/+Ar plasma

GaInP/InGaAs/GaAs pseudomorphic high electron mobility transistors (PHEMTs) were fabricated by BCl/sub 3/+Ar plasma etching. Photoreflectance (PR) was used to evaluate the quality of the etching surface. It was found that a sample dry-etched with a 6 sccm BCl/sub 3/ flow rate, a 4 sccm Ar flow rate, and a 100 W RF power (i.e. sample S/sub a/) has the smallest amount of damage. The DC and small signal RF characteristics of PHEMT Sa were superior to those of the wet-etched PHEMT S/sub 0/ and PHEMT S/sub b/ dry etched with pure BCl/sub 3/. The improvement is attributed to the lower parasitic source resistance associated with the tighter gate recess geometry of the plasma recess device.